Research Paper
Engineering
E-ISSN No : 2454-9916 | Volume : 3 | Issue : 5 | May 2017
STATIC ANALYSIS OF CABLE STAYED BRIDGE SYSTEM USING VARIOUS TYPES OF DECK PROFILES 1
2
Anand Soni | Dr. Ganesh Doiphode | Anil Kannauzia
3
1
M. Tech Student in Structural Engineering in Parul Institute of Technology, Waghodia. Associate Professor in Applied Mechanics in M.S University, Vadodara. 3 Assistant Professor in Structural Engineering Department in Parul Institute of Technology, Waghodia. 2
ABSTRACT The Innovative deck profile of cable-stayed bridge proposed here for an analysis of different types of deck profiles by using cable stayed bridge system. The prime objective of the present work is to model an optimized Cable Stayed Bridge with economized girder with various features, i.e. span to depth ratio as constant parameter an attempt is made here to check the cost economy, structural strength of proposed by bridge by checking a ratio of load carrying capacity to material requirement respectively. The complete work consist an analysis using commercial software (MIDAS CIVIL 2016). Static analysis of bridge with variation in deck profiles, i.e., PSC-I Deck, PSC-T beam, PSC-Box girders. Parametric study will be work out using various tabular and graphical form which highlights an objective based on costeconomy aspect in terms of strength, serviceability and economy respectively are the prime criterion. Here a geometry was taken of "Pandit Dindayal Upadhyay Cable Stayed Bridge" which is presently constructing on Tapi river across Athwa to Adajan. KEY WORDS: Cable-Stayed bridge, Single Pylon, PSC-box Deck, PSC-T Deck, PSC-I Deck Static Analysis, IRC Standard, Self Anchored Suspension type. I. INTRODUCTION Cable-stayed bridges are large and sophisticated structures which may greatly benefit from the use of structural optimization techniques for preliminary design improvement. Many cable-stayed bridges have been built in the last few decades because of development in: (1) materials, (2) construction techniques, and (3) computation capabilities. The deck of cable-stayed bridge is elastically supported along the girder length by inclined stay. Therefore, the girders take not only bending moments, as in regular bridges but also significant axial forces from the inclined cables. Cablestayed bridge girders carrying both axial forces and bending moments. The structural behavior of cable-stayed bridges is sensitive to the load distribution between the girders, pylons, and cables. The determination of pre-tensioning cable stresses is critical in the cable-stayed bridge design procedure. By finding the optimum stresses in cables, the load and moment distribution of the bridge can be improved. In recent years, different research works have studied iterative and modern methods to find optimum stresses of cables. Prestressing is a very powerful technique that consist of introducing a set of stresses into a structure to improve the structural performance during its service life. This technique has allowed the construction of efficient structures, leading to more economical, slender, and durable with longer span bridges. In this paper, the present work is to model an optimized Cable Stayed Bridge with economized girder with sustainable features. By keeping span to depth ratio as constant parameter an attempt is made here to check the cost effectiveness, struc-
tural strength of proposed by bridge with checking a ratio of load carrying capacity to material requirement respectively. The complete work consists an analysis using commercial software(MIDAS CIVIL 2016). The total focus has been given to the static analysis of bridge with variation in deck profiles, i.e., PSC-I Deck, PSC-T beam, PSC-Box girders. For the present work geometry was taken of "Pandit Dindayal Upadhyay Cable Stayed Bridge" which is constructing on Tapi river across Athwa to Adajan. II. GEOMETRY OF BRIDGE Total span = 300 m. Main span = 150 m. Side span = 75 m. ( 2 x 75m = 150 m). Number of pylon : 2 Nos. Number of lane : 4 Number of cable plane : 1 Number of cable : 24 Nos. III. STRUCTURAL MODEL CONFIGRUATION A three dimensional finite element model was ready in MIDAS CIVIL 2016 software, which is a advanced software of design in India for cable stayed bridge analysis. The following table indicates the material properties and sectional properties were used to prepare a model : (see table :1 and 2)
Table No 1 : Material properties Material Name
Type
Standard
Grade
Elasticity (kN/m2)
Poisson Ratio
Density (kN/m3)
PSC 4-cell Box Girder
PSC
IS(PSC)
M 50
2.947e+01
0.17
2.39e+001
PSC 1-cell Box Girder
PSC
IS(PSC)
M 50
2.947e+01
0.17
2.39e+001
PSC Multi-T Girder
PSC
IS(PSC)
M 50
2.947e+01
0.17
2.39e+001
PSC Multi-I Girder
PSC
IS(PSC)
M 50
2.947e+01
0.17
2.39e+001 2.50e+001
Pylon
Concrete
IS(RC)
M 50
3.535e+007
0.2
Pylon-1
Concrete
IS(RC)
M 50
3.535e+007
0.2
2.50e+001
Cable
Steel
IS(S)
Fe 540
2.050e+008
0.3
7.688e+001
Cross beam
Concrete
IS(RC)
M 50
3.535e+007
0.2
2.50e+001
Table No 2 : Sectional properties Section Name PSC 4-cell Box Girder
Section Dimension Width (m)
Height (m)
23.50
3
Type
Area (m2)
Izz (m4)
PSC Box
29.47
1078.4
PSC 1-cell Box Girder
23.50
3
PSC Box
39.30
2063
PSC Multi-T Girder
23.50
3
PSC Box
19.9
276.3
CopyrightŠ 2016, IERJ. This open-access article is published under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License which permits Share (copy and redistribute the material in any medium or format) and Adapt (remix, transform, and build upon the material) under the Attribution-NonCommercial terms.
International Education & Research Journal [IERJ]
227
Research Paper
E-ISSN No : 2454-9916 | Volume : 3 | Issue : 5 | May 2017
PSC Multi-I Girder
23.50
3
PSC Box
18.65
323
Pylon
3(1.5)
4.5(1.5)
Hollow Rectangular
11
9.91
Pylon-1
3
4.5
Solid Rectangular
13.5
Cable
0.2
Solid circular
3.14e-02
10 7.85e-05
Cable
0.22
Solid circular
3.80e-02
1.149e-04
Solid circular
4.15e-02
1.373e-04
Solid Rectangular
6.0e-02
2.0e-04
Cable
0.23
Cross Beam
0.2
0.3
Table No 3 : Load Combination
Figure 1 : Elevation layout of "PANDIT DINDAYAL UPADHYAY Cablestayed Bridge”
Load
Value
Dead load
Calculate by software.
Secondary Dead load
55.76 kN/m.
Moving Load
Class A + Class AA loading
Ÿ SIDL Calculation(Super Imposed Dead Load) : SIDL Loads like Barriers, Footpath and kerb is generally taking as 0.5 kN/m2 u.d.l. with entire Span. Now, Asphalt Density = 2200 kN/m2
Assume, Wearing Coat = 80 mm SIDL Load = 22 x 0.08 = 1.76 kN/ m2 Total SIDL Load = 1.76 + 0.5 = 2.26 kN/m2 Figure 2 : Dimension of PSC 4-cell box Girder
Total Width of Deck = 23.5m SIDL Load along deck = 23.5 x 2.26 = 53.11 kN/m Total Factored SIDL = 1.5 x 53.11 = 55.76 kN/m
Figure 3 : Dimension of PSC 1-cell box Girder
4.1 STATIC EFFECTS IN BRIDGE COMPLETION STAGE Figure-6 Shows axial force in girder. The origin of the horizontal axis is the same as the x-axis in figure –1. I. Girder Axial Force : For M 50 grade PSC, Maximum allowable stress,
Figure 4 : Dimension of PSC T Girder
= 0.33 x fck
IRC-18 : 2000
= 0.33 x 50
Pg. No. : 9
= 16.5 N / mm2 First, Stress in N / mm2 converted into kN/m2 = 16500 kN /m2 Second, Stress converted into force Girder Stress = 1. 4-cell Box Girder Force = Girder stress x area = 16500 x 29.47 = 486255 kN
Figure 5 : Dimension of PSC I Girder The following conditions and assumptions are used in the modeling process : 1.
2. 1-cell Box Girder Force = Girder stress x area = 16500 x 39.30
The moving load used as per IRC 6 : 2014 Section : II LOADS AND STRESSES specifications Class AA Loading.
= 648450 3. Multi-T Girder Force = Girder stress x area
2.
The Secondary Dead load is 55.76 kN/m.
3.
The Yield Stress of cable is 1860Mpa.
= 16500 x 19.9
4.
The Girder PSC grade is M 50 with design allowable stress is 16.5Mpa.
= 328350 kN
5.
The pylon concrete grade is M50.
4. Multi-I Girder Force = Girder stress x area = 16500 x 18.65
The various type of girders are shown in above figures.
= 307725 kN The girder depth is 3m for all type of girder and schematic diagram and detailed summary shown in above figures. The pylon shape is single type with cable arrangement system is fan system. The cables are high strength parallel strength with yield stress 1860Mpa. IV. STATIC ANALYSIS Static analysis is done by MIDAS CIVIL 2016 Software under load combination of dead load and moving load shown in the figure.
228
1.) 4-cell Box Girder : At Pylon, The Girder force = 69278.48 kN 69278.48 < 486255 kN. =O.K
International Education & Research Journal [IERJ]
Research Paper
E-ISSN No : 2454-9916 | Volume : 3 | Issue : 5 | May 2017 4.) PSC Multi-I Girder :
2.) 1-cell Box Girder : At near to Pylon in the main span,
Near to Pylon,
The Girder force = 71456.08 kN
4.79 Mpa < 16.5 Mpa = O.K
71456.08 < 648450 kN.
Figure-7 shows that the maximum compressive girder stress at the pylon in 4-cell box girder and 1-cell box girder. In PSC multi-T type girder compressive girder stress occur at mid of the main span. And in PSC multi-I type girder compressive girder stress also occur at mid of the main span. In these four type of deckprofiles, girder axial stress satisfy with allowable compressive stress as per IRC criteria, which are shown in Table-5.
=O.K 3.) Multi-T Girder : At near to Pylon in the main span, The Girder force = 21635.33 kN 21635.33< 328350 kN. =O.K 4.) Multi-T Girder : At near to Pylon in the main span, The Girder force = 20933.7 kN 20933.7 < 307725 kN. =O.K
Figure 7 : Axial stress of girder under combination effect of dead load + secondary dead load + moving load Table 5 : Comparison of Girder Axial Stress (N/mm2) Allowable Girder Stress(N/mm2)
Girder Stress(N/mm2)
Check
PSC 4-cell Box Girder PSC 1-cell Box Girder
16.5 16.5
2.35 2.33
ok ok
PSC Multi-T Girder
16.5
4.55
ok
PSC Multi-I Girder
16.5
4.79
ok
Type of Girders
III. Girder bending Moment : Figure 6 : Axial force of girder under combination effect of dead load + secondary dead load + moving load Table 4 : Comparison of Girder Force (kN) Type of Girders
Allowable Girder Force (kN)
Girder Check Force(kN)
PSC 4-cell Box Girder
486255
69278.48
ok
PSC 1-cell Box Girder
648450
71456.08
ok
PSC Multi-T Girder PSC Multi-I Girder
328350 307725
21635.33 20933.7
ok ok
It indicate that the maximum girder axial force is more near to the pylon which is in compression. Table-4 indicates the comparison of girder forces of various type of deck profiles. Figure 8 : Girder bending moment under combination effect of dead load + secondary dead load + moving load
II. Girder Stress : For M-50 grade PSC, Maximum allowable stress,
Table 6 : Comparison of Girder Bending Moment (kN.m)
= 0.33 x Fck = 0.33 x 50 2
= 16.5 N / mm
1.) 4-cell Box Girder :
IRC-18 : 2000 Pg No. : 9
At Pylon, 2.35 Mpa < 16.5 Mpa = O.K
Type of Girders
Max. Girder Bending Moment(kN.m)(-)
Min. Girder Bending Moment(kN.m)(-)
PSC 4-cell Box Girder PSC 1-cell Box Girder
52500 96200
1500 1300
PSC Multi-T Girder PSC Multi-I Girder
27300 25400
1660 1140
2.) 1-cell Box Girder : At Pylon, 2.33Mpa < 16.5 Mpa = O.K 3.) PSC Multi-T Girder : At mid of the main span, 4.55 Mpa < 16.5 Mpa = O.K
International Education & Research Journal [IERJ]
229
Research Paper
E-ISSN No : 2454-9916 | Volume : 3 | Issue : 5 | May 2017 In the terms of girder bending moment result of PSC multi-I girder and PSC multi-T girder are giving better performance under combination of dead load, secondary dead load and moving load respectively.
IV. Cable Stress :
According to overall performance based analysis, PSC multi-cell box girder for four lane road in cable-stayed bridge system is proposed. VI. Future Work : Further research is needed in the following aspect of crossing cable stayed bridge. 1.
Non-linear effects
2.
Performance under wind
3.
Earthquake loading
REFERENCES : [1] AASTHO-LRFD specifications 7th Edition -2016 [2] IRC 6 : 2014 Section-II LOADS AND STRESSESS [3] IRC - 18 : 2000 Design criteria for pre-stressed road bridges [4] IRC 112 : Code for practice concrete road bridges
Figure 9 : Cable stress under combination effect of dead load + secondary dead load + moving load(Class A + Class AA)
[5] Do Dai Thang, Min-se Koo, Asif Hameed (2009), “Optimum Cost Design of Steel Box-Girder by Varying Plate Thickness”, KSCE Journal of Civil Engineering Department of Civil Engineering Inha University, Incheon 402-571.
Table 7 : Comparison of Cable Stress (N/mm2)
[6] L.M.C Simoes, J.H.J.O Negrao (2000), " Optimization of Cable Stayed Bridge With Box Girder Deck", Advance in Engineering Software(ELSEVIER).
Type of Girders
Allowable Cable Stress(N/mm2)
Max. Cable Stress(N/mm2)
Check
PSC 4-cell Box Girder
744
606
ok
PSC 1-cell Box Girder
744
663
ok
PSC Multi-T Girder PSC Multi-I Girder
744 744
679 681
ok ok
We are using parellal strand and its yield stress of cable is 1860 N/mm2. Under dead load + secondary dead load + Moving load allowable stress is = 0.4 x Yeild stress of cable. = 0.4 x 1860 = 744 N/mm2.
[7] Phani Kumar.Ch, S.V.V.K. Babu and D. Aditya Sai Ram (2016)," Analysis and Design of Prestressed Box Girder Bridge by IRC : 112-2011", International Journal of Constructive Research in Civil Engineering, Civil Engg. Department, Andhra Pradesh, India. [8] Xialin Yang And Yaping WU and Guoxiang WEI, (2010), " Analysis of Stress Influence of Top Deck Thickness on Main girder With box cross section used in cable stayed bridge", Logistics for Sustained Economic Development(ASCE) Civil Engineering College, Lanzhou University, Lanzhou 730070, China. [9] Yutaka Okamoto, Shunichi Nakamura (2011),“Static And Seismic Studies on Steel / Concrete Hybrid Towers for multi-span Cable-stayed Bridge”, Civil Engineering Course, Graduate School Of Engineering, Tokai University, Hiratsuka, Japan.(Science direct-(ELSEVIER)-Journal of construction steel research) [10] Yasir I. Musa and Manuel A. Diaz (2008), " Design Optimization of Composite Steel Box Girder in Flexure", Practice Periodical on Structural Design and Construction(ASCE). Engineer in Training, Federal Highway Administration, Harrisburg, PA 17107.
Figure-9 shows the comparision between cable stress of various type of deck profiles. Table 7 indictae the maximum cable stress occur in various deck profiles. It is indicate that the maximum cable stress in PSC multi-I girder compare to remaining deck-profiles. And the minimum stress occur in PSC 4cell box girder. 4.2 Effects in Operation Stage Under the combined effect of dead load, secondary dead load and moving load(Class A + Class AA) maximum girder axial force occurs at pylon in 4-cell box girder, near to pylon at side span in 1-cell box girder, and at main span in PSC multi-T type girder or PSC multi-I type girder, which are shown in Table-4. The maximum axial stress under the combined effect of dead load +SIDL+ moving load is occurs at pylon in PSC 4-cell box girder and PSC 1-cell box girder. In PSC multi-T girder and PSC multi-I girder maximum axial stress occurs in the main span. Comparison of girder axial stress describe in Table-5, which are also in the range of allowable axial stress as per IRC criteria. In PSC 4-cell box girder and in PSC 1-cell box girder the maximum bending moment under combination of dead load + secondary dead load + moving load occurs near to pylon in side span. In PSC multi-T girder and in PSC multi-I girder the maximum bending moment occur near the abutment. Under the combined effect of dead load and moving load the Maximum compressive stress of pylon is 9.19Mpa, 8.50Mpa, 9.73Mpa, and 9.42Mpa in PSC 4-cell box girder, PSC 1-cell box girder, PSC multi-T girder, PSC multi-I girder respectively. Under the combined effect of dead load and moving load the maximum stress of cable is 606Mpa, 663Mpa, 679Mpa, 681Mpa of PSC 4-cell box girder, PSC 1cell box girder, PSC multi-T girder, PSC multi-I girder respectively, which are smaller than the allowable stress of cable 744MPa. V. Conclusion : By keeping span to depth ratio constant for the analysis of various deck profiles under the load combination stress, force and bending moment are within the permissible limits as per IRC based codal criteria. By keeping constant span to depth ratio cable diameter is changing significantly, but pylon dimensions are same. By performance based analysis in the term of cable stress and girder stress, PSC multi-cell box girder is giving better performance.
230
International Education & Research Journal [IERJ]